It was one of the most surprising moments of the second debate between Nigel Farage and Nick Clegg. In a discussion about immigration, the Lib Dem leader whipped out a Ukip leaflet that compared British people to the plight of Native Americans.

"Let me just show you, this is a leaflet from Ukip," Clegg said, brandishing the leaflet. "It says here – it’s a picture of a very unhappy looking native American – is says, 'he used to ignore immigration, now he lives on a reservation.'

"The suggestion being that if we ignore immigration the British people will be cooped up on reservations. Nigel Farage, we are not – by staying in the European Union we are not going to be cooped up on a native American reservation. What are you going to say next? That you’re Crazy Horse or Sitting Bull? We’ve got to have a level-headed debate about this."

Farage claimed he did not know the leaflet. "I don’t recognise that leaflet," he said. "All sorts of things get put out, I don’t recognise that leaflet. I certainly wouldn’t endorse its sentiments."

As detailed in the gallery below, the Native American leaflet is from a 2010 Ukip campaign in Lancaster.